JP2005167161A - Method of manufacturing solar battery module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing solar battery module by which the series resistance of a solar battery module can be reduced when the module is constituted. <P>SOLUTION: The method of manufacturing the solar battery module includes a step (1) of respectively overlaying conductive sheets on the rear surfaces of a plurality of solar battery cells, a step (2) of partially fixing the overlaid conductive sheets to the rear surfaces of the solar battery cells, and a step (3) of arranging the solar battery cells in adjoining states and electrically connecting adjacent solar battery cells to each other in series. The method also includes a step (4) of encapsulating the serially connected solar battery cells by means of a light-transmissive encapsulating member. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for manufacturing a solar cell module, and more particularly to a method for manufacturing a solar cell module in which series resistance when modularized is reduced.

As a prior art related to the present invention, a solar battery module in which a solar battery matrix in which a plurality of solar battery cells are connected in series, parallel or series-parallel is sealed with a transparent resin or sheet, and the acrylic battery plate is attached to the solar battery cell. The thing which stuck the protection board like this and prevented the crack of each cell which arises during a solar cell module assembly process is known (for example, refer patent document 1).
JP 61-108178 A

  In general, in the field of solar cell modules, attempts have been made to keep the series resistance low by using a low-resistance material for the light-receiving surface electrode and back electrode of each solar cell and the interconnector connecting adjacent solar cells. .

As the simplest method, there is a method of reducing the series resistance by increasing the cross-sectional area of the interconnector.
However, when the cross-sectional area of the interconnector is increased, shadow loss increases, which may adversely affect the photoelectric conversion characteristics of the solar battery cell.
In addition, the stress when connected to the solar battery cell increases, which may lead to cell warpage or cracking.
Furthermore, workability when the interconnector is connected to the light-receiving surface electrode and the back surface electrode may be deteriorated.

Since the width and thickness of the interconnector are determined by the balance of these various factors, it is practically difficult to reduce the series resistance simply by increasing the cross-sectional area of the interconnector.
In recent years, the area of solar cells has been increased from the viewpoint of production efficiency and the like, and accordingly, the value of current generated from the solar cells and the solar cell modules has increased.
For this reason, the power loss due to the series resistance when modularized is relatively large.

  The present invention has been made in view of the above circumstances, and provides a method for manufacturing a solar cell module in which series resistance when modularized is reduced.

  The present invention includes (1) a step of superposing conductive sheets on the back surfaces of a plurality of solar cells, (2) a step of partially fixing the superposed conductive sheets on the back surfaces of the solar cells, 3) A step of arranging a plurality of solar cells so as to be adjacent to each other and electrically connecting the adjacent solar cells, and (4) a step of enclosing the solar cells connected in series with a translucent sealing member. The manufacturing method of a solar cell module provided with this is provided.

According to the present invention, the series resistance of the solar battery module can be reduced by a very simple operation of partially fixing the conductive sheet to the back surface of the solar battery cell.
In addition, since the conductive sheet is flexible and rich in flexibility, the workability is good. Furthermore, the stress applied to the solar battery cell is minimized, and the solar battery cell is not warped or cracked.

  The manufacturing method of the solar cell module according to the present invention includes (1) a step of superimposing conductive sheets on the back surfaces of a plurality of solar cells, and (2) partial overlapping of the conductive sheets on the back surface of each solar cell. (3) a step of arranging a plurality of solar cells adjacent to each other and electrically connecting the adjacent solar cells in series; and (4) translucency of the solar cells connected in series. The step of enclosing with the enclosing member is provided.

In the method for manufacturing a solar cell module according to the present invention, as the solar cell, one having a light receiving surface electrode and a back electrode formed on the front and back surfaces of the photoelectric conversion layer can be used.
As the photoelectric conversion layer, for example, a p-type or n-type silicon substrate having a thickness of about 200 to 400 μm and an n-type or p-type impurity diffused to form a pn junction layer can be used.

  As the light-receiving surface electrode, for example, a metal paste containing metal powder such as silver powder or aluminum powder is printed on the surface of the photoelectric conversion layer in a comb shape by a method such as a screen printing method, and is fired. be able to.

  As the back electrode, for example, a metal paste containing a metal powder such as silver powder or aluminum powder is printed on almost the entire back surface of the photoelectric conversion layer by a method such as a screen printing method and is used by firing. Can do.

  In addition, as a means for connecting adjacent solar cells in series with each other, for example, an elongated thin plate-like interconnector made of a conductive metal such as copper or aluminum can be used.

In the method for manufacturing a solar cell module according to the present invention, after the steps (1) and (2) are sequentially performed, the steps (3) and (4) may be sequentially performed.
In the method for manufacturing a solar cell module according to the present invention, after the step (3) is performed, the steps (1) and (2) may be sequentially performed, and then the step (4) may be performed. .
That is, the step of partially fixing each conductive sheet on the back surface of each solar cell and the step of connecting adjacent solar cells in series do not have a specific order. It may be the destination.

  Specifically, in the method for manufacturing a solar cell module according to the present invention, one end portion of the interconnector is previously bonded to the back surface of each solar cell, and a conductive sheet is overlaid on the back surface of the plurality of solar cells (1 ) Is a step of stacking each conductive sheet on the back surface of each solar cell from above the interconnector, and the step (3) of electrically connecting adjacent solar cells in series is each solar cell. The process of joining the other end part of the said interconnector joined to the back surface of this to the surface of the adjacent photovoltaic cell may be sufficient.

  In the method for manufacturing a solar cell module according to the present invention, the step (3) of electrically connecting adjacent solar cells in series includes both ends of the interconnector on one surface and the other back surface of the adjacent solar cells. The step (1) of superimposing the conductive sheets on the back surfaces of the plurality of solar cells respectively connects the conductive sheets to the back surfaces of the solar cells connected in series by the interconnector. It may be a step of overlapping from above the connector.

Moreover, in the manufacturing method of the solar cell module by this invention, the electroconductive sheet may consist of metal foil.
In this case, the metal foil may consist of any one of copper foil, silver foil, and aluminum foil. Further, the thickness may be 10 to 50 μm.

  Moreover, in the manufacturing method of the solar cell module by this invention, an electroconductive sheet may be fixed to the back surface of each solar cell by any one of solder, an electroconductive paste, and an adhesive tape.

  Here, the back surface of each solar cell specifically refers to the surface of the interconnector joined to the back electrode, the surface of the back electrode, or the outer edge of the back surface of the photoelectric conversion layer and the outer edge of the back electrode. Any of the surface of the exposed part partitioned into two may be sufficient. There may be at least one fixing point, and preferably two or more.

It should be noted that the partially fixed state is a temporarily fixed state, and if it is used in this state, the portion of the conductive sheet that is not fixed to the solar cells may be turned up. There is also.
However, even in a partially fixed state, once encapsulated in the encapsulating member, there is no possibility that the conductive sheet is turned up from the back electrode.
From another point of view, fixing (bonding) the entire surface of the conductive sheet to the back surface of the solar battery cell can be said to be a very wasteful operation considering that it will be sealed later by the sealing member.

  This invention is one of the features that changed the way of thinking that it is sufficient if the conductive sheet does not come off the back surface of the solar battery cell before being sealed by the sealing member. By keeping the fixing points of the conductive sheet to the minimum necessary, the series resistance when modularized is reduced while achieving very simple and good workability.

Moreover, in the manufacturing method of the solar cell module by this invention, each electroconductive sheet may have a dimension substantially the same as the back surface of each solar cell.
The size of each conductive sheet is preferably as large as possible from the viewpoint of lowering the series resistance. However, if the size is larger than the size of the solar battery cell, the portion protruding from the solar battery cell comes into contact with the light receiving surface side and leaks. It does not get up or have a good design, so it does not have the same shape and area as the solar cells.

Moreover, in the manufacturing method of the solar cell module by this invention, each electroconductive sheet may have any one of a notch part and an opening part.
According to such a configuration, in the step of encapsulating the solar battery cell on which the conductive sheet is stacked with the encapsulating member, the cut portion or the opening formed in the conductive sheet serves as an air vent.
For this reason, it is prevented that the encapsulating member encloses bubbles between the back surface of the solar battery cell and the conductive sheet, and adhesion between the back surface of the solar battery cell and the conductive sheet is improved.

  Embodiments of the present invention will be described below in detail with reference to the drawings.

Solar Cell A solar cell used in the method for manufacturing a solar cell module according to Example 1 of the present invention will be described with reference to FIGS. 1 is a side view of a solar battery cell used in the method for manufacturing a solar battery module according to Example 1, and FIG. 2 is a bottom view of the solar battery cell shown in FIG.

As shown in FIGS. 1 and 2, a solar battery cell 10 used in the method for manufacturing a solar battery module according to Example 1 includes a photoelectric conversion layer 11 and a light-receiving surface electrode 12 formed on the surface of the photoelectric conversion layer 11. A back electrode 13 formed on the back surface of the photoelectric conversion layer 12, an interconnector 14 joined to the back electrode 13, and a copper foil (conductive sheet) 15 covering the back electrode 13 from above the interconnector 14. I have.
The back electrode 13 is composed of a back surface aluminum electrode 13a formed on substantially the entire back surface side of the photoelectric conversion layer 11 and a back surface silver electrode 13b formed in the opening of the back surface aluminum electrode 13a. Is connected to the back silver electrode 13b. An antireflection film 18 is formed on the surface of the photoelectric conversion layer 11.

The copper foil 15 has a thickness of 17 μm and is partially fixed to the interconnector 14 by the solder 16. Further, the copper foil 15 has a cross-shaped cut portion 17 for improving the adhesion to the back surface aluminum electrode 13a and the interconnector 14 in a later modularization step.
In this embodiment, the interconnector 14 and the copper foil 15 are already attached in a cell state, but of course, the interconnector 14 and the copper foil 15 may be attached after moving to the modularization process.
Although not shown, a conductive paste or double-sided tape may be used in place of the solder 16 as a means for fixing the copper foil 15. Further, an opening may be formed in the copper foil 15 instead of the cut portion 17.

Manufacturing of Solar Battery Cell A manufacturing method of the solar battery cell 10 shown in FIGS. 1 and 2 will be described with reference to FIG.
First, as shown in FIG. 3A, the photoelectric conversion layer 11 is formed by diffusing n-type impurities into a p-type semiconductor substrate having a thickness of about 200 to 400 μm.
Next, as shown in FIG. 3B, an antireflection film 18 made of SiNx, SiOx, or the like is formed.

Next, as shown in FIG. 3C, a metal paste containing aluminum powder is printed on almost the entire back surface of the photoelectric conversion layer 11 by a screen printing method, and baked to form a back surface aluminum electrode 13a. Further, a metal paste containing silver powder is printed by screen printing, and the back surface silver electrode 13b for connecting the interconnector 14 is formed on the back surface side of the photoelectric conversion layer 11, and the comb-shaped electrode 12 is formed on the light receiving surface side by firing. .
Next, as shown in FIG. 3D, the interconnector 14 is soldered to the back surface silver electrode 13b.

Next, as shown in FIG. 3 (e), the copper foil 15 is overlaid on the back surface aluminum electrode 13a and the interconnector 14, and the overlapped copper foil 15 is partially fixed to the interconnector 14. The solar battery cell 10 shown in FIG. 2 is completed.
As shown in FIG. 2, the copper foil 15 is fixed to the interconnector 14 by attaching the copper foil 15 previously attached with solder to two places in contact with the interconnector 14, the back surface aluminum electrode 13 a and the interconnector 14. It is carried out by superimposing and partially soldering to the interconnector 14 by heating the solder attachment portion. As shown in FIG. 2, a part of the interconnector 14 is sufficient for soldering.

Manufacture of Solar Cell Module A method for manufacturing a solar cell module using the solar cells 10 shown in FIGS. 1 and 2 will be described with reference to FIG.
First, as shown in FIG. 4A, the solar cells 10 manufactured through the solar cell manufacturing process described above are arranged so as to be adjacent to each other, and one interconnector 14 of the adjacent solar cells 10 is arranged. Are soldered to the other light receiving surface electrode 12 and connected in series to produce a solar cell string 26.

In addition, in the said process, the solar cell 10a to which the external terminal 21 for electric power extraction was connected instead of the interconnector 14 other than the solar cell 10 to which the interconnector 14 was connected is also used.
The solar battery cell 10 a to which the external terminal 21 is connected is disposed at one end of the solar battery string 26.
The solar battery cell 10 a disposed at one end of the solar battery string 26 includes a copper foil 15 like the other solar battery cells 10, and the copper foil 15 covers the back surface aluminum electrode 13 a from above the external terminal 21. .

  Next, as shown in FIG. 4B, the external terminal 21 is soldered to the light receiving surface electrode 12 of the solar battery cell 10 located at the other end of the solar battery string 26.

Next, as shown in FIG. 4C, the solar cell string 26 is encapsulated by a translucent encapsulating member 22 made of EVA. At this time, the glass plate 23 is attached to the light receiving surface side, and the weather-resistant back film 24 is attached to the back surface side at the same time.
When encapsulating with EVA, the notch 17 (see FIG. 2) formed in the copper foil 15 serves to remove air bubbles, so that air bubbles remain between the copper foil 15, the back surface aluminum electrode 13a and the interconnector 14. The copper foil 15 is encapsulated by the encapsulating member 22 in close contact with the back surface aluminum electrode 13a and the interconnector 14.
Thereafter, as shown in FIG. 4D, a frame member 25 made of aluminum is attached to the periphery to complete the solar cell module 20.

  In addition, in this Example, although the solar cell 10 with which the interconnector 14 and the copper foil 15 were already attached in the cell state is used, of course, after moving to a modularization process, the interconnector 14 and the copper foil 15 are Each may be attached. In that case, after connecting the adjacent solar cells with the interconnector 14, the copper foil 15 is stacked on the back surface aluminum electrode 13a, and a predetermined portion is fixed with solder, conductive paste, double-sided tape or the like.

Comparative Example A solar battery cell as a comparative example with respect to Example 1 will be described with reference to FIGS. 10 and 11.
As shown in FIGS. 10 and 11, the solar battery cell 50 according to the comparative example is different from that of the first embodiment only in that the copper foil covering the back surface aluminum electrode 53 a is not provided. This is the same as the cell 10 (see FIGS. 1 and 2).

Example 1 and Comparative Example of Comparative Example In order to compare the solar cell 10 according to Comparative Example 1 (see FIGS. 1 and 2) and the solar cell 50 according to Comparative Example (see FIGS. 10 and 11), Example 1 1-cell modules (not shown) are respectively produced from the solar cells 10 and 50 of the comparative example, and the characteristic change from the cell state to the module state is compared.
The 1-cell module is a module composed of one solar battery cell, and is the same as the solar battery module 20 shown in FIG. 4D except that there is one solar battery cell. It has a configuration.

  First, various characteristics of the solar cells 10 and 50 according to Example 1 and the comparative example are respectively measured. In order to clarify the effect of the copper foil 15 in the module state, the solar cell of Example 1 For 10, various characteristics are measured before the copper foil 15 is attached. In addition, measurement is performed on nine solar cells 10 and 50 in both Example 1 and Comparative Example, and an average value is calculated for each measured item.

After measuring various characteristics of the cell state, a copper foil 15 covering the back electrode 13 is attached to the solar battery cell 10 of Example 1, and nine single-cell modules are obtained. On the other hand, after measuring various characteristics, the solar battery cell 50 of the comparative example is directly used as nine 1-cell modules.
In both Example 1 and the comparative example, after being made into a one-cell module, the same items as those measured in the cell state are measured, and the average value of nine units is calculated for each measured item. Thereafter, the rate of change (module state / cell state) with respect to the measurement value in the cell state is calculated for each measurement item. The results are shown in Table 1 below.

In Table 1, Isc is a short-circuit current, Voc is an open circuit voltage, F.I. F is the fill factor and Pm is the maximum power.
As shown in Table 1, the module state Isc is increased by nearly 10% with respect to the cell state in both Example 1 and Comparative Example. This is because the use of a highly reflective white back film for the back film of the module and the single cell module resulted in an apparent illuminance when the exposed area of the white back film was larger than the cell area. It is because it became high.
F.F. F is greatly lowered by setting the module state. This is due to an increase in series resistance due to the connection of the external terminal.

  Next, Table 2 below shows the rate of change (Example 1 module change rate / comparative example module change rate) of each measurement item of the 1 cell module change rate according to Example 1 with respect to the 1 cell module change rate according to the comparative example. Note that the rate of change is calculated assuming that the measured value of each item of the 1-cell module according to the comparative example is 1.

As shown in Table 2, for Isc and Voc, there is no difference in the rate of change in characteristics from the cell state to the module state in both Example 1 and Comparative Example.
However, by covering the back electrode with copper foil as in Example 1, the series resistance in the module state is reduced, and compared with the comparative example in which the copper foil is not used. F and Pm are each improved by 1.2%.

A solar battery cell used in Example 2 of the present invention will be described with reference to FIGS. FIG. 5 is a side view of the solar battery cell used in Example 2, and FIG. 6 is a bottom view of the solar battery cell shown in FIG.
As shown in FIG. 5 and FIG. 6, the solar battery cell 30 used in Example 2 is formed by interposing copper foil 15 as in the solar battery cell 10 used in Example 1 (see FIGS. 1 and 2). Rather than being partially soldered to the connector 14, the copper foil 35 is partially fixed to the outer edge of the back surface aluminum electrode 33a and the exposed portion 31a of the back surface of the photoelectric conversion layer 31 with an adhesive tape 36. 1 and different. Other configurations are the same as those of the solar battery cell 10 used in the first embodiment.

Comparison of Example 1 and Example 2 For comparison with a one-cell module (not shown) produced using the solar cell 10 according to Example 1, the solar cell 30 according to Example 2 is also made of copper foil. Before attaching 35, Isc, Voc, F. Measure for each characteristic of F and Pm.
Then, the copper foil 35 is attached, a 1 cell module (not shown) is produced, the same items as those measured in the cell state are measured, and the rate of change with respect to the cell state is calculated.

FIG. 7 is a graph comparing the rate of change of the 1-cell module according to Example 2 with the rate-of-change range of the nine 1-cell modules according to Example 1 described above.
As shown in FIG. 7, the Isc change rate (A1), Voc change rate (A2), F.I. The F change rate (A3) and the Pm change rate (A4) are the Isc change rate range (B1), Voc change rate range (B2), F. They are within the F change rate range (B3) and the Pm change rate range (B4), respectively. From this, it can be seen that the fixing means and fixing position of the copper foils 15 and 35 do not affect the rate of change from the cell state to the module state.
In other words, as in the second embodiment, the effect of reducing the series resistance as in the first embodiment can be achieved by simply fixing the copper foil 35 to a part of the back surface of the photoelectric conversion layer 31 with the adhesive tape 36. Is obtained.

A solar battery cell used in Example 3 of the present invention will be described with reference to FIGS. 8 is a side view of the solar battery cell used in Example 3, and FIG. 9 is a bottom view of the solar battery cell shown in FIG.
As shown in FIG. 8 and FIG. 9, the solar battery cell 40 used in Example 3 is formed by interposing copper foil 15 as in the solar battery cell 10 (see FIGS. 1 and 2) used in Example 1. The second embodiment is different from the first embodiment in that the copper foil 45 is partially fixed to the back surface aluminum electrode 43a with the conductive paste 46 instead of being partially soldered to the connector 14. Other configurations are the same as those of the solar battery cell used in Example 1.
Although not shown, a double-sided tape may be used instead of the conductive paste 46.

It is a side view of the photovoltaic cell used with the manufacturing method of the photovoltaic module by Example 1 of this invention. It is a bottom view of the photovoltaic cell shown by FIG. It is process drawing which shows the manufacturing process of the photovoltaic cell shown by FIG. 1 and FIG. FIG. 5 is a process diagram illustrating a manufacturing process of the solar cell module according to Example 1. It is a side view of the photovoltaic cell used in Example 2 of this invention. FIG. 6 is a bottom view of the solar battery cell shown in FIG. 5. It is a graph which compares the characteristic change rate from the cell state of the photovoltaic cell used in Example 1, and the photovoltaic cell used in Example 2 to a module state. It is a side view of the photovoltaic cell used in Example 3 of this invention. It is a bottom view of the photovoltaic cell shown in FIG. It is a side view of the photovoltaic cell by a comparative example. It is a bottom view of the photovoltaic cell shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10, 10a, 30, 40, 50 ... Solar cell 11, 31 ... Photoelectric conversion layer 12 ... Light-receiving surface electrode 13 ... Back surface electrode 13a, 33a, 43a, 53a ... Back surface aluminum electrode 13b ... Back side silver electrode 14 ... Interconnector 15, 35, 45 ... Copper foil 16, 46 ... Solder 17 ... Notch part 18 ... Antireflection film 20 ... Solar cell module 22 ... Encapsulating member 23 ... Glass plate 24 ... Back film 25 ... Frame material 26 ... Solar cell string 31a ... Exposed part 36 ... Adhesive tape 46 ... Conductive paste

Claims (9)

(1) a step of superimposing conductive sheets on the back surfaces of a plurality of solar cells,
(2) a step of partially fixing the stacked conductive sheets to the back surface of each solar battery cell;
(3) A step of arranging a plurality of solar cells adjacent to each other and electrically connecting adjacent solar cells in series;
(4) A method for manufacturing a solar cell module, comprising a step of enclosing solar cells connected in series with a translucent enclosing member.   The method for manufacturing a solar cell module according to claim 1, wherein the steps (3) and (4) are sequentially performed after the steps (1) and (2) are sequentially performed.   The method for manufacturing a solar cell module according to claim 1, wherein after the step (3) is performed, the steps (1) and (2) are sequentially performed, and then the step (4) is performed.   The method for manufacturing a solar cell module according to any one of claims 1 to 3, wherein each conductive sheet is fixed to the back surface of each solar cell by any one of solder, a conductive paste, and an adhesive tape.   The method for manufacturing a solar cell module according to claim 1, wherein each conductive sheet has substantially the same dimensions as the back surface of each solar cell.   Each electroconductive sheet is a manufacturing method of the solar cell module as described in any one of Claims 1-5 which has any one of a cut | notch part and an opening part.   Each electroconductive sheet is 10-50 micrometers in thickness, The manufacturing method of the solar cell module as described in any one of Claims 1-6.   Each electroconductive sheet consists of metal foil, The manufacturing method of the solar cell module as described in any one of Claims 1-7.   The method for manufacturing a solar cell module according to claim 8, wherein the metal foil is one of a copper foil, a silver foil, and an aluminum foil.

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